Digital BW, The Print

>Joe, do tell  !!
...

Yes, please.

Some have found the Hydrocote to clog easily in the nozzles, but there may
be procedures and types of sprayers that avoid this.

Some of the HVLP (what does that stand for?) sprayers apparently only work
for spraying vertical surfaces.  Yet, some like to lay the print flat and
"pool" the PUR to get a heavy, single coat.

Some of the general painting literature says that with water-based PUR, the
second and third coats should be applied only when the first is completely
dry and then only after the first is prepared physically or chemically so
that the subsequent coats will stick.  I suspect that the adherence concern
is for high-gloss surfaces, but it would be interesting to know if there are
any separation issues.  Frankly, with cross-linking going on for 7 days, I
don't see why the layers would not attach themselves to each other if done
after dry by before fully cured.

I think one advantage of PUR is the relative lack of tackiness after the
curing period.  However, some have suggested that multiple coats might
result in this tackiness never going away -- or taking a very long time to
go away.  So, one test we ought to be doing is, after 7 days, stack
prints -- even try some face to face -- put books on them, and see if they
stick together after quite a period like that.

At any rate, thanks to all who are doing this PUR spraying work.  If it can
be made reliable and easy enough to be practical, the samples I've seen may
indicate it is a final step that really gets this medium up to and past the
silver print.

Paul
http://www.PaulRoark.com